ABSTRACT
Background: The influence of intravenous ferric carboxymaltose (FCM) on reverse electrical remodeling (RER) in patients with heart failure with reduced ejection fraction (HFrEF) post-cardiac resynchronization therapy (CRT) is unknown. This study examines the effect of iron replacement using intravenous FCM on RER in CRT-implanted HFrEF patients with iron deficiency anemia. Methods: We retrospectively analyzed 65 patients with successful CRT-defibrillator between March 2017 and January 2020, all with iron deficiency anemia at implantation. The cohort comprised 35 patients in the FCM group and 30 in the non-FCM group. Follow-up data were obtained from visits 6 months post-CRT implantation including baseline characteristics, echocardiographic left ventricular measurements, and electrocardiograms. Changes in intrinsic QRS duration (iQRS) and left ventricular ejection fraction (LVEF) from baseline to 6 months were assessed. Results: The FCM group showed a greater reduction in iQRS duration compared to the non-FCM group (-10.4 ± 2.2 ms vs. -3 ± 2.9 ms, p < 0.0001). Additionally, at the 6-month follow-up, the increase in LVEF was higher in the FCM group than in the non-FCM group (+3.6 ± 1.6% vs. -0.1 ± 1.7%, p < 0.0001). Correlations were found between changes in ferritin levels and iQRS duration (r = -0.725, p < 0.0001) and LVEF (r = 0.712, p < 0.0001). Multivariate regression analysis revealed that elevated ferritin independently influenced the increase in LVEF (p = 0.006, ß = 0.554) and the decrease in iQRS (p < 0.001, ß = -0.685). Conclusions: Intravenous iron treatment with FCM may reduce iQRS duration and improve LVEF and functional status in HFrEF patients with iron deficiency anemia following CRT.
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RESUMEN Introducción : La terapia de resincronización cardíaca (TRC) se indica en pacientes que habitualmente presentan remodelado cardíaco generado por dilatación y disincronía contráctil. La TRC contribuye al remodelado reverso, relacionado con menor mortalidad y hospitalizaciones por insuficiencia cardíaca (IC). Se han observado además mejoras en la conducción intraventricular, con reducción del tiempo de activación. La cuantificación del remodelado eléctrico reverso se ha subutilizado como parámetro de respuesta, con escasos reportes sobre su asociación con la respuesta clínica-estructural. Objetivo : Analizar el remodelado eléctrico reverso intraventricular como parámetro de respuesta a la TRC. Métodos: Se incluyeron pacientes con más de 6 meses de implante. Se obtuvo un ECG con estimulación desactivada (QRS intrínseco, QRSi, post TRC), y por ecocardiograma transtorácico se definió la fracción de eyección ventricular izquierda (FEVI), el diámetro de fin de diástole del ventrículo izquierdo (DFDVI) y la presencia de insuficiencia mitral. Se clasificó a los pacientes según la respuesta clínica-estructural. El remodelado eléctrico se caracterizó con la comparación de la duración del QRS pre y post TRC y la valoración de los cambios del QRS (ΔQRSi) entre grupos. Resultados : Se incluyeron 23 pacientes. Un 39% presentó disminución >10 mseg del QRSi. Observamos un QRSi de -9,3 ± 20,7 mseg en respondedores, y 11,25 ± 18,9 mseg en no respondedores (p = 0,027), más acentuada en los hiper respondedores (ΔQRSi: -14,44 ± 17,40 mseg, p = 0,026). Las mujeres con QRS ≥150 mseg pre TRC exhibieron disminución significativa del QRSi (p = 0,0195). Conclusiones : El remodelado eléctrico reverso se comprobó en 39% de los pacientes que recibieron TRC. Observamos una relación significativa del QRSi con la respuesta clínica-estructural, mayor en hiper respondedores. Mujeres con QRS ancho pre-TRC exhiben remodelado eléctrico reverso más acentuado. Este es un parámetro de fácil acceso e interpretación durante los controles ambulatorios.
ABSTRACT Introduction : Cardiac resynchronization therapy (CRT) is indicated in patients who often present cardiac remodeling due to dilatation and contractile dyssynchrony. CRT contributes to reverse remodeling which is associated with reduced mortality and heart failure (HF) hospitalizations. Improvements in intraventricular conduction with decreased ventricular activation time have also been observed. The quantification of reverse electrical remodeling has been underused as a parameter of response, and there are few reports on its association with the clinical-structural response. Objective : To analyze intraventricular reverse electrical remodeling as a parameter of response to CRT in living individuals. Methods : We included patients implanted at least 6 months ago. A deactivated stimulation ECG (post-CRT intrinsic QRS) was obtained, and by means of transthoracic echocardiography (TTE), the left ventricular ejection fraction (LVEF), the left ventricular end-diastolic diameter (LVEDD) and the presence of mitral regurgitation were defined. Patients were classified according to their clinical-structural response. Electrical remodeling was characterized by comparing pre- and post-CRT QRS duration and assessing QRS changes (ΔiQRS) between groups. Results : A total of 23 patients were included, 39% of which showed a >10 ms decrease in iQRS. We observed a iQRS of -9.3±20.7 ms in responders, and of 11.25±18.9 ms in non-responders (p=0.027), more marked in hyper-responders (ΔiQRS: -14.44±17.40 ms, p=0.026). Women with pre-CRT QRS ≥150 ms showed a significant decrease in iQRS (p=0.0195). Conclusion : Reverse electrical remodeling was found in 39% of the patients under CRT. We noted a significant relationship between iQRS and clinical-structural response, higher in hyper-responders. Women with wider pre-CRT QRS showed more marked reverse electrical remodeling. This parameter is accessible and easy to read in outpatient visits.
ABSTRACT
INTRODUCTION: Effects of cardiac resynchronization therapy (CRT) on arrhythmogenicity and sudden death have not been fully ascertained. CRT has been shown to increase transmural dispersion of repolarization (TDR) immediately on implantation, which may favorably remodel on long-term follow-up. However, such a hypothesis has not been prospectively evaluated. METHODS AND RESULTS: We included 35 consecutive patients who underwent CRT implantation between September 2013 and August 2014 (mean age 56.8 ± 11.09 years; 71.43% males). QT and Tpeak-Tend (Tp-e) intervals were measured during endocardial (RVendoP), epicardial (LVepiP), and biventricular pacing (BiVP) at CRT implantation and 1-year follow-up. Compared to RVendoP (130.41 ± 16.75 ms), Tp-e was significantly prolonged during BiVP (142.06 ± 21.98 ms; P < 0.001) and LVepiP (183.45 ± 27.87 ms; P < 0.001) at baseline. There was a significant decrease in Tp-e during BiVP on follow-up (117.93 ± 15.03 ms; P < 0.001). High responders had significantly lower Tp-e at 1 year compared to low responders (113.16 ± 14.3 ms vs 129.59 ± 9.75 ms, P = 0.004). Tp-e at 1 year had strong negative correlation with reduction in LV end-systolic volumes (r = - 0.51; P = 0.003). Seven patients with sustained ventricular arrhythmias during follow-up had significantly longer baseline Tp-e compared to those without arrhythmias (158.19 ± 17.59 ms vs 139.72 ± 20.94 ms, P = 0.043). A baseline Tp-e value of ≥ 148 ms had a specificity of 75% and sensitivity of 71% to predict ventricular arrhythmias. CONCLUSIONS: Baseline TDR is greater during BiVP and LV epiP compared with RVendoP in patients with heart failure. However, BiVP causes a significant reduction in TDR reflective of reverse electrical remodeling on long-term follow-up.
